Planarizing element for thermal printing of color filter

ABSTRACT

A planarizing element is described for use in a thermal imaging process. The planarizing element includes a support; a planarizing layer comprising a crosslinkable binder having a weight average molecular weight of about 20,000 to about 110,000.

FIELD OF THE INVENTION

This invention relates to improved products and processes for effectinglaser-induced thermal transfer imaging in the formation of colorfilters. The invention is of particular utility in the formation ofcolor filters in high resolution liquid crystal displays.

BACKGROUND OF THE INVENTION

Liquid crystal display (LCD) devices have become increasingly importantin displays that require very low consumption of electrical power orwhere the environment dictates a lightweight, planar, flat surface. Forexample, LCDs are used in display devices such as wristwatches, pocketand personal computers, flat panel television displays and aircraftcockpit displays. When there is a need to incorporate a color displaycapability into such display devices, a component called a color filteris used. For the device to have color capability, each LCD pixel isaligned with a color area, typically red, green, or blue, of a colorfilter array. Depending upon the image to be displayed, one or more ofthe pixel electrodes is energized during display operation to allow fulllight, no light, or partial light to be transmitted through the colorfilter area associated with that pixel. The image perceived by a user isa blend of colors formed by the transmission of light through adjacentcolor filter areas. A major contributor to the cost of color LCDs is thecolor filter. Four color filter manufacturing methods are known in theart, viz., dye gelatin, pigmented photoresist, electrodeposition andprinting. The pigmented photoresist method offers the best trade-off ofdegradation resistance, optical properties, and flexibility along withhigh resolution, and is generally preferred. While conventionalphotolithographic materials and methods may be employed in thephotoresist method, it suffers from the high cost and inconvenienceassociated with numerous process steps, some involving wet chemistry.

Laser-induced thermal transfer processes are well-known in applicationssuch as color proofing and lithography and have been described in, forexample, Baldock, U.K. Patent 2,083,726; DeBoer, U.S. Pat. No.4,942,141; Kellogg, U.S. Pat. No. 5,019,549; Evans, U.S. Pat. No.4,948,776; Foley et al., U.S. Pat. No. 5,156,938; Ellis et al., U.S.Pat. No. 5,171,650; and Koshizuka et al., U.S. Pat. No. 4,643,917.

As is known in the art, laser-induced processes use a laserableassemblage comprising (a) a donor element containing the material to betransferred in contact with (b) a receiver element. The laserableassemblage is exposed to a laser, usually a suitable spatially modulatednear-infrared laser, resulting in transfer of material from the donorelement to the receiver element. To form an image, exposure takes placeover a small region of the laserable assemblage at any one time, so thattransfer of material from the donor element to the receiver element canbe built up one pixel at a time. In this context the term pixelindicates the minimum addressable writing area of the laser exposuresystem. This laser addressable pixel size is generally smaller than theLCD color pixel size described above. Computer control of the writinglaser produces transfer with high resolution and at high speed. Thelaserable assemblage, upon imagewise exposure to a laser as describedsupra, is henceforth termed an imaged laserable assemblage.

For the preparation of images for proofing applications and in photomaskfabrication, the colorant comprises a pigment or a dye. For thepreparation of lithographic printing plates, the colorant comprises anoleophilic material that will receive and transfer ink in printing.

Laser-induced processes are fast and result in transfer of material withhigh resolution. However, in many cases, the resulting transferredmaterial does not have the required durability. In dye sublimationprocesses, light-fastness is frequently lacking. In ablative and melttransfer processes, poor adhesion and/or durability can be a problem. InU.S. Pat. No. 5,563,019 and U.S. Pat. No. 5,523,192, improved multilayerlaserable assemblages and associated processes are disclosed that doafford improved adhesion and/or durability of the transferred images. InU.S. Pat. No. 6,051,318 an improved donor film for use in the productionof color filters is disclosed. U.S. Pat. No. 6,143,451 discloses alaser-induced thermal image transfer imaging process characterized bythe use of an ejection layer that affords advantages in the final imagedproduct.

As is known in the art, the thermally imageable layer in a laserableassemblage always contains some sort of binder, generally a polymericbinder. The binder serves to hold together the colorant and anyadjuvants thereto before, during and after the image transfer process iseffected, forming a single cohesive, homogeneous mass. It is found thatthe physical properties of the binder have significant effect on theproperties of the transferred image. In particular, it has been found inthe practice of the art that binders characterized by glass transitiontemperatures near or below room temperature provide good toughness anddurability with superior adhesive properties, but often at the expenseof resolution. On the other hand, binders characterized by glasstransition temperatures well above room temperature provide superiorresolution but at the expense of toughness, durability, and adhesion.Practical application of laser-induced thermal image transfer to highresolution applications such as color filter formation requirestoughness and adhesion sufficient to permit survival of the transferredimage during the remainder of the manufacturing process. The resolutionrequirements for the color filter application are extremely demanding,and little trade-off can be made while preserving utility in theapplication.

Aqueous blends of colloidally dispersed polymers for use in makingorganic coatings which are hard and ductile at ambient temperature andwhich remain stiff and elastic at elevated temperature are disclosed inMazur et al, U.S. Pat. No. 6,020,416. The combination of properties isattributed to the use of blends of high molecular weight polymersdiffering in glass transition temperature.

A need exists for stable crosslinked pigmented images on a substratewherein the surface of the image away from the substrate is an extremelysmooth surface.

SUMMARY OF THE INVENTION

Improved products and processes for laser induced thermal imaging aredisclosed herein.

In a first aspect, this invention provides a planarizing elementcomprising a planarizing layer, wherein the planarizing layer comprisesa crosslinkable binder, and wherein the crosslinkable binder has aweight average molecular weight of about 20,000 to about 110,000. Moretypically, the crosslinkable binder has a weight average molecularweight of about 30,000 to about 100,000, and still more typically about50,000 to about 85,000.

In a second aspect, the invention provides a method for making a colorimage comprising: (1) imagewise exposing to laser radiation a laserableassemblage comprising: (A) a donor element comprising a thermallyimageable layer, and (B) a receiver element comprising: (a) a receiversupport; and (b) an image receiving layer provided on the surface of thereceiver support; whereby the exposed areas of the thermally imageablelayer are transferred to the receiver element to form acolorant-containing image on the image receiving layer; and (2)separating the donor element (A) from the receiver element (B), therebyrevealing the colorant-containing image on the image receiving layer ofthe receiver element; (3) optionally applying, typically laminating, thecolorant-containing image on the image receiving layer of the receiverelement to a permanent substrate, and removing the receiver support totransfer the colorant-containing image on the image receiving layer tothe permanent substrate, and (4) applying a planarizing elementcomprising a support and a planarizing layer to the colorant-containingimage, and removing the support, wherein the planarizing layer isadjacent the colorant-containing image, and wherein the planarizinglayer comprises a crosslinkable binder having a weight average molecularweight of about 20,000 to about 110,000. More typically, thecrosslinkable binder has a weight average molecular weight of about30,000 to about 100,000, and still more typically about 50,000 to about85,000.

In the second aspect, the receiver support or the permanent substratemay be made of a transparent material such as glass or a rigid plasticsuch as polycarbonate. When step (3) is optional, the receiver supportis a transparent material. Alternately, the thermally imageable layer,the image receiving layer, or both may comprises a crosslinkable binderhaving a number average molecular weight of about 1,500 to about 70,000,more typically about 5,000 to about 10,000, and most typically 10,000 toabout 70,000.

In a third aspect, the invention provides a method for making a colorimage comprising:

(1) imagewise exposing to laser radiation a laserable assemblagecomprising: (A) a donor element having a thermally imageable layer, and(B) a permanent substrate; whereby the exposed areas of the thermallyimageable layer are transferred to the permanent substrate to form acolorant-containing image on the permanent substrate; (2) separating thedonor element (A) from the permanent substrate (B), thereby revealingthe colorant-containing image on the permanent substrate; and (3)applying a planarizing element comprising a support and a planarizinglayer to the colorant-containing image, and removing the support,wherein the planarizing layer is adjacent the colorant-containing image,and wherein the planarizing layer comprises a crosslinkable binderhaving a weight average molecular weight of about 20,000 to about110,000. The permanent substrate may be glass or treated glass.Alternately, the permanent substrate may be a rigid plastic, e.g.polycarbonate, or treated rigid plastic. More typically, thecrosslinkable binder has a weight average molecular weight of about30,000 to about 100,000, and still more typically about 50,000 to about85,000.

In a fourth aspect, the invention provides a color liquid crystaldisplay comprising a color filter, wherein the color filter is preparedusing a thermal imaging process, and a planarizing element comprising aplanarizing layer having a crosslinkable binder having a weight averagemolecular weight of about 20,000 to about 110,000. More typically, thecrosslinkable binder has a weight average molecular weight of about30,000 to about 100,000, and still more typically about 50,000 to about85,000.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of an LCD displayincorporating the color filter of this invention.

FIG. 2 is a simplified schematic diagram of an assemblage comprising adonor element and a receiver element for use in the thermally imagingprocess of the invention.

FIG. 3 illustrates the receiver element of FIG. 2 after exposure andseparation from the donor element, wherein the receiver elementcomprises a receiver support, which may be glass, and carries a colorimage transferred from the thermally imageable layer of the donorelement.

FIGS. 4 illustrates the receiver element of FIG. 2 after exposure andseparation from the donor element, wherein the receiver element carriesa color image transferred from the thermally imageable layer of thedonor element, and the transfer of said color image to a permanentsubstrate.

FIG. 5 a is the layout of a drum type thermal imager.

FIG. 5 b is the layout of a flat bed thermal imager.

FIG. 6 shows the orientation of color stripes to the peel direction.

FIG. 7 shows schematic cross-section of the color filter pattern onglass showing the arrangement of the planarizing layer.

FIG. 8 is an illustration of the lamination stack used for lamination ofthe planarizing layer to the color filter in a press.

FIG. 9 is a comparison graph showing the effect of thickness andmolecular weight on planarizing effectiveness

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, a color filter is prepared bya thermal transfer process, and then overlaid with additional layers toform a liquid crystal display. An assemblage is provided comprising adonor element and a receiver element. Planarizing elements may be usedin forming the color filter.

Planarizing Element

The planarizing element comprises a support and a planarizing layer.

Planarizing Support

The support of the planarizing element is a dimensionally stable sheetmaterial. Typically, the planarizing element is flexible to facilitatesubsequent processing steps, as described further, below. Examples oftransparent, flexible films appropriate for use as the support include,for example, polyethylene terephthalate (“polyester”), polyethersulfone, polyimides, poly(vinyl alcohol-co-acetal), polyolefins, orcellulose esters, such as cellulose acetate, and polyvinyl chloride.Typically, the support of the planarizing element is polyethyleneterephthalate that may optionally been plasma treated. Other materialscan be present as additives in the support, as long as they do notinterfere with the essential function of the support. Examples of suchadditives include plasticizers, coating aids, flow additives, slipagents, antihalation agents, antistatic agents, surfactants, and otherswhich are known for use in the formulation of films. The supportgenerally has a thickness in the range of 25-200 microns, preferably75-125 microns.

Planarizing Layer

The planarization layer (40) protects the underlying color filterelement and smoothes and/or levels the surface. Materials useful asplanarization layers comprise a low molecular weight crosslinkablebinder having a weight average molecular weight of about 20,000 to about110,000. More typically, the crosslinkable binder has a weight averagemolecular weight of about 30,000 to about 100,000, and still moretypically about 50,000 to about 85,000. The binders may be film formingand coatable from solution or from a dispersion. Binders having glasstransition temperatures below about 110° C. are preferred.

Process steps used to convert color filters into LCD panels ofteninvolve contact of the color filter with organic solvents such asN-methylpyrrolidinone, γ-butyrolactone, acetone, isopropanol, etc. Sincethese solvents swell, or even dissolve, the low molecular weight binderresins used in the planarizing layer (40), some form of crosslinkingcapability must be provided.

Some suitable pairs of functional groups for such crosslinking reactionsinclude: hydroxyl and isocyanate; hydroxyl and carboxyl; hydroxyl andmelamine-formaldehyde; carboxyl and melamine-formaldehyde; carboxyl andamine; carboxyl and epoxy, epoxy and amine; and carboxylic anhydride andamine. The pairs of crosslinking functional groups can be utilized inseveral ways. One crosslinking functional group can be incorporated intothe binder polymer backbone, and the other added as a polyfunctional lowmolecular weight crosslinking agent. One crosslinking functional groupcan be incorporated into the binder polymer backbone, and the otherincorporated into a different binder polymer backbone. Both of thecrosslinking functional groups can be incorporated into the same binderpolymer backbone.

Another crosslinking reaction involves one or more of the polymericbinders having pendant groups that are capable of undergoingfree-radical induced or cationic crosslinking reactions. Pendant groupswhich are capable of undergoing free-radical induced crosslinkingreactions are generally those which contain sites of ethylenicunsaturation, such as mono- and poly-unsaturated alkyl groups; acrylicand methacrylic acids and esters. In some cases, the pendantcrosslinking group can be photosensitive, as is the case with pendantcinnamoyl or N-alkyl stilbazolium groups. Pendant groups which arecapable of undergoing cationic crosslinking reactions includesubstituted and unsubstituted epoxide and aziridine groups.

Additional components may include the coating aids, UV stabilizers,UV-filters, UV absorbers, small molecule crosslinking aids,plasticizers, flow additives, adhesion promoters, antistatic agents,surfactants, and others which are known for use in the formulation offilms, with the proviso they are colorless. Small molecule crosslinkingaids such as multifunctional acids in conjunction with epoxy containinglatexes may be used.

Donor Element

The donor element (10) comprises a thermally imageable layer (12)comprising at least one crosslinkable polymeric binder and a firstcolorant, and a base element. The base element comprises a base support(14) and an optional heating layer (16) between the base support (14)and the thermally imageable layer (12). As best seen in FIG. 2, the basesupport (14) provides support for the heating layer (16), if present,and the thermally imageable layer (12). Optionally, an ejection layer(not shown) may be present in the donor element.

Base Support

The base support (14) of the donor element (10) is a dimensionallystable sheet material. Typically, the donor element (10) is flexible tofacilitate subsequent processing steps, as described further, below. Thebase support (14) is transparent to laser radiation to allow forexposure of the thermally imageable layer (12), as described further,below.

Examples of transparent, flexible films appropriate for use as the basesupport (14) include, for example, polyethylene terephthalate(“polyester”), polyether sulfone, polyimides, poly(vinylalcohol-co-acetal), polyethylenes, or cellulose esters, such ascellulose acetate, and polyvinyl chloride. Typically, the base support(14) of the donor element (10) is polyethylene terephthalate that hasbeen plasma treated to accept the optional heating layer (16). Othermaterials can be present as additives in the base support, as long asthey do not interfere with the essential function of the support.Examples of such additives include plasticizers, coating aids, flowadditives, slip agents, antihalation agents, antistatic agents,surfactants, and others which are known for use in the formulation offilms. The base support generally has a thickness in the range of 25-200microns, preferably 38-102 microns.

Heating Layer

As best seen in FIG. 2, the function of the optional heating layer (16)of the donor element (10) is to absorb the laser radiation (L) used toexpose the thermally imageable layer (12) and to convert the radiationinto heat. The heating layer is typically a metal.

Some examples of other suitable materials are transition metal elementsand metallic elements of Groups 13, 14, 15 and 16, their alloys witheach other, and their alloys with the elements of Groups 1 and 2, whichhave less adhesion to the thermally imageable layer (12), or may betreated to have less adhesion, than the adhesion of the thermallyimageable layer (12) to the receiving surface of the substrate (24) andabsorb the wavelength of the laser. The IUPAC numbering system is usedthroughout, where the groups are numbered from left to right as 1-18(CRC Handbook of Chemistry and Physics, 81^(st) Edition, 2000). Tungsten(W) is an example of a suitable transition metal.

Carbon, a Group 14, nonmetallic element, may also be used.

Nickel, aluminum, chromium and nickel vanadium alloys are typical metalsfor the heating layer (16). Chromium applied by sputtering is the mosttypical choice for the heating layer.

Alternatively, in FIG. 2, the optional heating layer (16) can be anorganic layer comprising an organic binder and an infrared absorber.Some examples of suitable binders include polyvinyl chloride,chlorinated polyvinyl chloride and nitrocellulose. Examples of nearinfrared absorbers are carbon black and infrared dyes. Polymers withhigher decomposition temperatures may also be employed in fabricatingorganic heating layers.

The thickness of the heating layer (16) depends on the opticalabsorption of the metals used. The most preferred metallization is suchas to give 50% optical transmission at 830 nm, with a preferred rangefrom 25% to 60% T.

Although it is preferred to have a single optional heating layer, it isalso possible to have more than one heating layer, and the differentlayers can have the same or different compositions.

The optional heating layer (16) may be applied to the base support (14)by a physical vapor deposition technique. The term “physical vapordeposition” refers to various deposition approaches carried out invacuum. Thus, for example, physical vapor deposition includes all formsof sputtering, including ion beam sputtering, as well as all forms ofvapor deposition, such as electron beam evaporation and chemical vapordeposition. A specific form of physical vapor deposition useful in thepresent invention is RF magnetron sputtering. Nickel may be electronbeam deposited onto the base support (14). Aluminum may be applied byresistive heating. Chromium, nickel and nickel vanadium layers may beapplied by either sputtering or electron beam deposition. In the case ofoptional heating layers comprised of organic layers, the heating layermay be applied by conventional solvent coating techniques.

Thermally Imageable Layer

In a first embodiment, the thermally imageable layer of the presentinvention may comprise (a) two or more polymeric binders at least onepair of which said binders differ in glass transition temperature(T_(g)) by at least 20 centigrade degrees, and (b) a colorant.Preferably the binders differ in T_(g) by at least 40 centigradedegrees. Most preferably the binders differ in T_(g) by at least 80centigrade degrees.

The higher T_(g) binder of the pair exhibits a T_(g) of between 20 and140 centigrade degrees higher than the T_(g) of the lower T_(g) binderin the pair. The T_(g) of the higher T_(g) binder in the pair rangesfrom 70° C. to 140° C. The T_(g) of the lower T_(g) binder of the pairranges from −40° C. to 60° C. Preferably the T_(g) of the higher T_(g)binder of the pair ranges from 100° C. to 140° C. Preferably the T_(g)of the lower T_(g) binder of the pair ranges from −40° C. to 0° C.

The polymeric binder suitable for use in the present inventionpreferably does not self-oxidize, decompose or degrade at thetemperatures to which it exposed during the laser exposure so that thecolorant and binder are transferred with little or no degradation.Binder polymers suitable for use as the high T_(g) component of the pairinclude, but are not limited to, polystyrene and copolymers thereof,acrylates, methacrylates and co-polymers thereof. Binder polymerssuitable for use as the low T_(g) component of the pair include but arenot limited to butyl acrylates and co-polymers thereof. The monomerunits present in the polymeric binders suitable for use in the presentinvention may be substituted or unsubstituted. Mixtures of polymers canalso be used.

In a preferred embodiment, 1-5 mol-% of crosslinkable monomers areincorporated into the polymeric binders of the instant invention. Aftercrosslinking, the binders exhibit resistance to the temperatures andsolvents employed in the formation of color filter arrays in liquidcrystal display devices, making this embodiment highly preferred in thatapplication. Suitable crosslinkable comonomers include but are notlimited to methacrylic acid and glycidyl methacrylate.

The polymeric binders suitable for use in the present invention arepresent at a concentration of about 15-50% by weight, preferably 30-40%by weight, based on the total weight of the thermally imageable layer.The weight ratio of higher T_(g) binder to lower T_(g) binder should bein the range of 60:40 to 95:5, preferably in the range of 75:25 to 92:8.

The binders suitable for use in the present invention are synthesizedpreferably in the form of latex dispersions, as described in Mazur etal. U.S. Pat. No. 6,020,416, incorporated herein by reference to theentirety, and as hereinbelow exemplified. The synthesis of polymerlatexes is a very well-known art in widespread commercial use.

In a preferred embodiment, one or more of the polymeric binders comprisemonomer units having pendant groups that are capable of undergoingfree-radical induced or cationic crosslinking reactions. Pendant groupswhich are capable of undergoing free-radical induced crosslinkingreactions are generally those which contain sites of ethylenicunsaturation, such as mono- and polyunsaturated alkyl groups; acrylicand methacrylic acids and esters. In some cases, the pendantcrosslinking group can be photosensitive, as is the case with pendantcinnamoyl or N-alkyl stilbazolium groups. Pendant groups which arecapable of undergoing cationic crosslinking reactions includesubstituted and unsubstituted epoxide and aziridine groups.

Crosslinkable binders suitable for the practice of the invention can beformed by direct copolymerization of one or more ethylenicallyunsaturated dicarboxylic acid anhydrides, or the corresponding alkyldiesters, with one or more of the above comonomers. Suitableethylenically unsaturated dicarboxylic acid anhydrides are, for example,maleic anhydride, itaconic acid anhydride and citraconic acid anhydrideand alkyl diesters such as the diisobutyl ester of maleic anhydride. Thecopolymer binder containing acid anhydride functionality can be reactedwith primary aliphatic or aromatic amines.

Alternately, the thermally imageable layer may comprise a low molecularweight crosslinkable binder having a number average molecular weight ofabout 1,500 to about 70,000.

The total binder concentration is generally in the range of about 15-50%by weight, based on the total weight of the thermally imageable layer,preferably 30-40% by weight.

The colorant in the thermally imageable layer may be a pigmentdispersion or a non-sublimable dye. As is well known in the art, theintroduction of pigments into the film compositions is most readilyaccomplished by employing pigment dispersants to prepare stable pigmentdispersions. It is preferred to use a pigment as the colorant forstability and for color density, and also for the high decompositiontemperature. The pigment is preferably chosen from pigments having (1)high transparency, and (2) small particle size, wherein the averageparticle size is less than about 100 nanometers. Some useful chemicalclasses of pigments include metal-containing phthalocyanines andhalogenated derivatives, anthraquinones, pyrazolones, acetoacetylmonoazo, bisazo, and methine. Some examples of transparent pigments thatcan be used in this invention include RS Magenta 234-007™, GS Cyan249-0592™, and RS Cyan 248-061, from Sun Chemical Co. (Fort Lee, N.J.);BS Magenta RT-333D , Microlith Yellow 3G-WA™, Microlith Yellow 2R-WA™,Microlith Blue YG-WAT™, Microlith Black C-WA™, Microlith Violet RL-WA™,Microlith Red RBS-WA™, Cromophthal Red 3B, Irgalite Blue GLO, andIrgalite Green 6G, from Ciba (Newport, Del.); Fanchon Fast Yellow 5700,from Bayer (Pittsburgh, Pa.); any of the Heucotech Aquis II™ series; anyof the Heucosperse Aquis III™ series; and the like.

The amount of colorant present in the thermally imageable layer ischosen such that transmission optical densities of the final colorfilter image prepared upon the permanent substrate satisfactorilyreproduces the required color gamut for the LCD display which will beconstructed using the color filter. The color gamut for LCD displays istypically described using CIE chromaticity coordinates x, y and Y. Whilenot intended to be limiting, typical donor element transmission opticaldensities are in the range from about 1.0 and about 2.5 for red, blueand green at the visible wavelength absorption maxima of the pigments,and between about 3.0 and about 4.0 for black at 550 nm. In general, thecolorant is present in an amount of from about 20 to about 80% byweight, typically about 30 to about 50% by weight, based on the totalweight of the transfer coating.

A dispersant is usually present when a pigment is to be transferred, inorder to achieve maximum color strength, transparency and gloss. Thedispersant is generally an organic polymeric compound and is used toseparate the fine pigment particles and avoid flocculation andagglomeration. A wide range of dispersants is commercially available. Adispersant will be selected according to the characteristics of thepigment surface and other components in the composition as practiced bythose skilled in the art. However, one class of dispersant suitable forpracticing the invention is that of the AB dispersants. The A segment ofthe dispersant adsorbs onto the surface of the pigment. The B segmentextends into the solvent into which the pigment is dispersed. The Bsegment provides a barrier between pigment particles to counteract theattractive forces of the particles, and thus to prevent agglomeration.The B segment should have good compatibility with the solvent used. TheAB dispersants of choice are generally described in “Use of AB BlockPolymers as Dispersants for Non-aqueous Coating Systems”, by H. C.Jakubauskas, Journal of Coating Technology, Vol. 58, No. 736, pages71-82. Suitable AB dispersants are also disclosed in U.K. Patent1,339,930 and U.S. Pat. Nos. 3,684,771; 3,788,996; 4,070,388; 4,912,019;and 4,032,698. Other types of dispersants include graft copolymerdispersants, and random copolymer dispersants. Conventional pigmentdispersing techniques, such as roll milling, media milling, ballmilling, sand milling, etc., can be employed. For color filterapplications, the binder polymer of the thermally imageable layer canalso act as a dispersant for the pigment.

Other materials can be present as additives in the thermally imageablelayer as long as they do not interfere with the essential function ofthe layer. Some examples of such additives include coating aids,plasticizers, flow additives, slip agents, antihalation agents,antistatic agents, surfactants, and others that are known for use in theformulation of coatings. However, it is preferred to minimize the amountof additional materials in this layer, as they may deleteriously affectthe final product after transfer to the final support.

The thermally imageable layer generally has a thickness in the range ofabout 0.1 to 5 microns, preferably in the range of about 0.1 to 1.5microns. Thicknesses greater than about 5 microns are generally notpreferred as they require excessive energy in order to be effectivelytransferred to the receiver and generally give poorly resolved images.

Although it is typical to have a single thermally imageable layer, it isalso possible to have more than one thermally imageable layer, and thedifferent layers can have the same or different compositions, as long asthey all function as described above. The total thickness of thecombined thermally imageable layers should be in the range given above.

The thermally imageable layer(s) can be coated onto the heating layer ofthe donor, if present, or directly on a support as a dispersion or asolution in a suitable solvent. Any suitable solvent can be used as acoating solvent, as long as it does not deleteriously affect theproperties of the assemblage, using conventional coating techniques orprinting techniques, for example, gravure printing or slot dye coating.

Additional Layers

An ejection layer (not shown) may optionally be provided between theoptional heating layer (16) and the thermally imageable layer (12), asis known in the art. The ejection layer decomposes into gaseousmolecules when heated, providing additional force to cause transfer ofexposed portions of the thermally imageable layer (12) to the receiverelement (20). A polymer having a relatively low decompositiontemperature (less than about 350° C., preferably less than about 325°C., and more preferably less than about 280° C.) may be used. In thecase of polymers having more than one decomposition temperature, thefirst decomposition temperature should be lower than 350° C. Suitableejection layers are disclosed in U.S. Pat. No. 5,766,819, assigned tothe assignee of the present invention. Thermal additives may also beprovided in the ejection layer to amplify the effect of the heatgenerated in the heating layer (16), as is known in the art and alsodescribed in U.S. Pat. No. 5,766,819. U.S. Pat. No. 5,766,819 isincorporated by reference herein. By providing an additionaldecomposition pathway for the creation of gaseous products, additionalpropulsive forces can be generated to assist in the transfer process.

Optionally, there may be a release means (not shown) provided betweenthe heating layer (16), if present, or the support (14) and thethermally imageable layer (12). This may be accomplished by oxygenplasma treating the heating layer (16) or the support (14). Alternately,release layers may be applied to either the heating layer (16), ifpresent, or the support (14) prior to application of the thermallyimageable layer (12). Some useful layers include hexamethyldisilazane(HMDS) available from Arch Chemicals, Inc., Norwalk Conn.,dichlorosilane perfluordecane, available from Gelest, Inc., Tullytown,Pa., tridecafluoro-1,1,2,2-tetrahydooctyl-1-methyldichlorosilane,available from United Chemical Technologies, Inc., Bristol, Pa., etc.Release means may also be a heat activated release material.

Other donor elements may comprise alternate thermally imageable layer orlayers on a support. Additional layers may be present depending of thespecific process used for imagewise exposure and transfer of the formedimages. Some suitable thermally imageable layers over which the overcoatdescribed above may be applied are disclosed in U.S. Pat. No. 5,773,188,U.S. Pat. No. 5,622,795, U.S. Pat. No. 5,593,808, U.S. Pat. No.5,334,573, U.S. Pat. No. 5,156,938, U.S. Pat. No. 5,256,506, U.S. Pat.No. 5,427,847, U.S. Pat. No. 5,171,650 and U.S. Pat. No. 5,681,681.

Receiver Element

The receiver element, illustrated in FIG. 2, comprises a receiversupport (22) and an image-receiving layer (24), and optionally a cushionor release layer (not shown).

The receiver support (22) can be made of the same materials as the basesupport of the donor element. In addition, opaque materials, such aspolyethylene terephthalate filled with a white pigment such as titaniumdioxide, or synthetic paper, such as Tyvek® spunbonded polyolefin may beused as the receiver support. Typical materials for the receiver support(22) are polyethylene terephthalate and polyimide. Alternately, when thereceiver element is used as the permanent substrate, the receiversupport may include transparent plastic films, as described above,glass, and composites thereof. Thin glass substrates (0.5-1.0 mm thick)are typically used.

The image-receiving layer (24) may be a coating of, for example, apolycarbonate; a polyurethane; a polyester; polyvinyl chloride;styrene/acrylonitrile copolymer; poly(caprolactone); vinylacetatecopolymers with ethylene and/or vinyl chloride; (meth)acrylatehomopolymers (such as butyl-methacrylate) and copolymers; and mixturesthereof. This image-receiving layer may be present in any amounteffective for the intended purpose. In general, good results have beenobtained at coating weights of 1 to 5 g/m². Alternately, the imagereceiving layer may comprise a low molecular weight crosslinkable binderhaving a number average molecular weight of about 1,500 to about 70,000.

In addition to the image-receiving layer, the receiver element mayoptionally include one or more other layers between the receiver supportand the image receiving layer. One additional layer between theimage-receiving layer and the support is a release layer. In theintermediate transfer process, where the receiver element is theintermediate transfer element, the release layer can provide the desiredadhesion balance to the receiver element so that the image-receivinglayer adheres to the receiver support during exposure and separationfrom the donor element, but promotes the separation of the imagereceiving layer from the receiver support upon transfer, for example bylamination, of the color image to a permanent support. The color imageis thus between the permanent support (e.g., glass or polarizingelement) and the image receiving layer. The image receiving layer canact as a planarizing layer for the LCD device. Examples of materialssuitable for use as the release layer include polyamides, silicones,vinyl chloride polymers and copolymers, vinyl acetate polymers andcopolymers and plasticized polyvinyl alcohols. The release layer canhave a thickness in the range of 1 to 50 microns.

A cushion layer that is a deformable layer may also be present in thereceiver element, typically between the release layer and the receiversupport. The cushion layer may be present to increase the contactbetween the receiver element and the donor element when assembled.Examples of suitable materials for use as the cushion layer includecopolymers of styrene and olefin monomers such asstyrene/ethylene/butylene/-styrene, styrene/butylene/styrene blockcopolymers, and other elastomers. An adhesive layer may be presentbetween the cushion layer and the release layer or between the cushionlayer and the image receiving layer. Examples of suitable adhesivesinclude hot melt adhesives such as ethylene vinyl acetate. Receivingelements suitable for use in color filter array applications aredisclosed as transfer elements in U.S. Pat. No. 5,565,301 which ishereby incorporated by reference. Typical polymers for the receiverlayer are (meth)acrylic polymers, including, but not limited to,acrylate homopolymers and copolymers, methacrylate homopolymers andcopolymers, (meth)acrylate block copolymers, and (meth)acrylatecopolymers containing other comonomer types, such as styrene. Alternatereceiver elements are disclosed in U.S. Pat. No. 5,534,387. Alternately,the image receiving layer may also contain a low molecular weightcrosslinkable binder similar to that described above.

Typically, the surface of the image receiving layer may be roughened toimprove its function. Methods of roughening the surface of the imagereceiving layer include micro-roughening. Micro-roughening may beaccomplished by any suitable method. One specific example, is bybringing it in contact with a roughened sheet typically under pressureand heat. The pressures used are preferably less than about 8 MPa.Optionally, heat may be applied up to about 80 to about 88° C. moretypically about 54° C. for polycaprolactone polymers and about 94° C.for poly(vinylacetate) polymers, to obtain a uniform micro-roughenedsurface across the image receiving layer. Alternatively, heated orchilled roughened rolls may be used to achieve the micro-roughening.

It is important that the means used for micro-roughening of the imagereceiving layer has uniform roughness across its surface. Typically theaverage roughness (Ra) as determined with a Wyko Profilometer (WykoModel NT 3300, Veeco Metrology, Tucson, Ariz.)) should yield values lessthan about 0.6μ.

Permanent Substrate

In the intermediate transfer process, the permanent substrate (30) usedin step (3) of the process must be optically transparent. Some examplesinclude transparent plastic films such as polyethylene terephthalate andpolyimide, glass, treated glass and composites thereof, or rigid plasticsuch as polycarbonate or poly(4-methylpentene). Thin glass substrates(0.5-1.0 mm thick) may be typically used.

The treatment or coating on the permanent substrate (30) may be selectedfrom the group consisting of a polycarbonate; a polyurethane; apolyester; polyvinyl chloride; styrene/acrylonitrile copolymer;poly(caprolactone); vinylacetate copolymers with ethylene and/or vinylchloride; (meth)acrylate homopolymers (such as butyl-methacrylate) andcopolymers; and mixtures thereof. This layer may be present in anyamount effective for the intended purpose. In general, good results havebeen obtained at coating weights of 1 to 5 g/m².

In the direct transfer process, the receiver element in step (2) is thepermanent substrate (30). The receiver support (22) and an optionalimage-receiving layer (24) comprise the materials described above forthe permanent substrate (30) and the treatment or coating thereon.

It may also be advantageous to employ a substrate that incorporates apre-formed black mask pattern. Typically, a pre-formed black mask isused in the case of rigid glass or plastic substrates, and also can beemployed with flexible permanent substrates or even with flexibleintermediate receiver supports. The black mask, which serves todelineate the colored (e.g. RGB) pixel structure of the color filter,may be prepared in various ways. One method of preparing the black maskmay employ thermal imaging donors of the type described herein. In thiscase the process of constructing the black mask follows the processesdescribed for imaging of the colored donor films to either intermediateor permanent substrates, with or without the optional image receivinglayer.

It is also possible to use a black mask that is preformed on thepermanent substrate by alternate conventional means well known to thoseskilled in the art. An example of a conventional method of producing ablack mask is a photolithographic process involving optical exposure ofa photoresist through an exposure mask. The black mask may be typicallyformed following additional processing steps (e.g. etching, washing,stripping, etc.). When employing a conventional pre-formed black mask,the colored thermal donor elements are exposed and transfer an image tothe permanent substrate (30) with preformed black mask in precisealignment to the preformed black mask. This process results in an‘hybrid’ color filter employing conventional black mask and thermalcolor pattern. The advantage of using a preformed black mask is thatthis process offers improved ease of integration into existing LCDmanufacturing processes. The preformed black mask also takes advantageof the inherently much higher resolution of optical lithographicprocesses in comparison to the thermal transfer process. A highresolution black mask can serve to decrease the resolution requirementof the colored portions of the color filter pattern as the lowerresolution edges of the color patterns are hidden by the black mask.Transfer of the colored donors in alignment with a preformed black maskmay require modification of the thermal imaging equipment to allow ameans for aligning the preformed black mask to the writing locations ofthe imager.

Typically a preformed conventional black mask pattern may be composed ofeither thin (ca. 0.1-0.3 microns) inorganic-materials (e.g. chromium,chromium oxide, etc.) or of organic black pigmented resist (organicblack mask). In the case of an organic black mask, typical thicknessesof the black mask layer may be in the range of 0.5-3.0 microns.Generally if the treatment or coating is present with a conventionallyprepared preformed black mask, the treatment or coating will be theoutermost layer of the permanent substrate (30) and will completelycover the preformed black mask.

Process

As shown in FIGS. 2, 5 a and 5 b, the outer surface of the thermallyimageable layer (12) of the donor element (10) is brought into closeproximity with the image receiving layer (24) of the receiving element(20) to form the assemblage (25). Vacuum and/or pressure can be used tohold the donor element (10) and the receiver element (20) together toform the assemblage (25). As another alternative, the donor element (10)and receiver element (20) can be taped together and taped to the imagingapparatus. A pin/clamping system can also be used. Alternatively, thesurface of the donor element and or the receiver element may beroughened during coating by laminating a matte polyethylene coversheet.This serves improve the average uniformity of the contact between thedonor element (10) and the receiver element (20), by facilitating theevacuation of air from between the donor element (10) and the receiverelement (20).

The assemblage (25) is then exposed through the donor element (10) inselected areas by radiation (L) in the form of heat or light. Asmentioned above, the exposure pattern is the desired pattern of thecolor filter. The optional heating layer (16) or the thermally imageablelayer absorbs the radiation (L), generating heat which causes transferof the heat-exposed portions of the thermally imageable layer (12) tothe receiver element (20).

After exposure, the donor element (10) is separated from the receiverelement (20). This may be done by peeling the two elements apart. Verylittle peel force is typically required; the donor support (10) maysimply be separated from the receiver element (20). Any conventionalmanual or automatic separation technique may be used. Best qualityimaging results are obtained when the process of separating the donorand receiver is performed with a consistent peel speed and radius ofcurvature with the direction of peeling oriented parallel to the colorfilter stripe pattern.

After separation of the donor element (10) and the receiver element(20), the color image is transferred to the receiver element, while theunexposed, unwanted portions of the thermally imageable layer (12)remain on the donor element,

The radiation (L) is typically provided by a laser. Laser radiation maybe provided at a laser fluence of up to about 1 J/cm², preferably about75-500 mJ/cm² Other techniques that generate sufficient heat to causetransfer of the colorant material layer may be used, as well. Forexample, a thermal print head, or microscopic arrays of metallic tipswith diameters ranging from about 50 nanometers, such as those used inatomic force microscopy, diameters ranging to about 5 microns, may alsobe used. An electric current is provided to the metallic tips togenerate the heat.

Various types of lasers may be used to expose the thermally imageablelayer (12) of colorant material. The laser preferably emits in theinfrared, near-infrared or visible region. Particularly advantageous arediode lasers emitting in the region of 750 to 870 nm which offer asubstantial advantage in terms of their small size, low cost, stability,reliability, ruggedness and ease of modulation. Diode lasers emitting inthe range of 780 to 850 nm are most preferred. Such lasers are availablefrom, for example, Spectra Diode Laboratories, San Jose, Calif. Othertypes of lasers may also be used, as is known in the art, providing thatthe absorption of the heating layer (16) matches the emitting wavelengthof the laser.

As shown in FIG. 5 a, if the donor element (10) and the receiver element(20) are both flexible, the assembly (25) can be conveniently mounted ona drum to facilitate laser imaging.

The transfer step can be repeated with the same receiver element bearingthe first color image (12′) and one or more different donor elementshaving a colorant of a different color, to prepare a multicolor colorfilter pattern. If the receiver support is the permanent substrate, thisforms a color filter (35) as shown in FIG. 3 and FIG. 7. Optionally, anadditional adhesive layer (not shown) may be present on the permanentsubstrate, e.g., glass, before transfer

As best seen in FIG. 4, if the receiver element is an intermediatetransfer element, the next step in the process of the invention is totransfer the color image (12′) from the receiver element to a permanentsubstrate, such as glass. After formation of the color image (12′),which may be a single color or multicolor image, on the receiver element(20), the receiver element (20), including the color image (12′), isbrought into contact with a permanent substrate (30), as shown in FIG.4. The substrate (30) may include a base element (32) and an adhesivecoating (34) to increase the adhesion of the patterned layer (12′) tothe substrate. The adhesive coating (34) may be a suitablepolycarbonate, a polyurethane, a polyester, polyvinyl chloride,styrene/acrylonitrile copolymer, poly(caprolactone), vinylacetatecopolymers with ethylene and/or vinyl chloride, (meth)acrylatehomopolymers (such as butyl-methacrylate), copolymers, and mixturesthereof. Alternately, an image receiving layer similar to that describedabove, for the receiving element, may be applied to the permanentsubstrate, by laminating a separate receiving element to the permanentsubstrate and removing, e.g. peeling, the receiver support, prior totransferring the color image to the permanent substrate.

It is important that the surface of the substrate (30) adjacent thecolor image have greater adhesion to the color image (12′) than theadhesion of the color image and image receiving layer to the receiversupport. The substrate (30) may be any material that will support thesubsequent layers and transmit light generated by LCD display. Somesuitable materials include transparent plastic films, as describedabove, glass, and composites. Thin glass substrates are preferred. Glassas thin as 50 microns can be used. The upper limit on thickness is setby the weight and desired properties of the end product. The thicknessis usually less than 5 millimeters. Typical values are from 0.5-1.0 mm.

Preferably, the color image (12′) is transferred to the substrate (30)by lamination. Nip or press lamination may be used, as is known in theart. A roll-to-roll HRL-24 Laminator, manufactured by DuPont,Wilmington, Del., is typically used to accomplish the lamination. Theminimum useful pressure is about 210 kPa. The maximum pressure isdetermined by the pressure at which unwanted contamination, such as aspeck of dust, can cause the substrate to crack. Generally the pressureshould be less than about 69 MPa. After separation of the donor element(10) from the substrate (30), the color image (12′) is transferred tothe substrate to form a color filter element (35).

The next step in the process of the invention is to apply aplanarization layer (40) to the so formed color filter.

The planarization layer (40) may be applied using any conventionalcoating technique. Such techniques are well known in the art and includespin coating, casting, gravure printing, and extrusion coatingprocesses. The planarization layer can also be applied as a preformedfilm and laminated to the color filter element (35) as shown in FIG. 8,wherein a stack comprising a rigid plate (61) such as a stainless steelplate; a release element (62) such as a Teflon® sheet; a flexiblecompressible element (63) such as a fiber reinforced rubber sheet; apolyester sheet (64); the planarizing element having a planarizing layer(40); color filter (35) with the color filter pattern adjacent theplanarizing layer (40); a polyester sheet (64′) adjacent the glasssubstrate of the color filter; a flexible compressible element (63′)such as a fiber reinforced rubber sheet; a release element (62′) such asa Teflon® sheet; and a rigid plate (61′) such as a stainless steelplate; is placed in a vacuum laminator and the chamber evacuated beforelamination of the planarizing layer to the color filter element (35)occurs.

Liquid Crystal Display

A simplified schematic representation of a liquid crystal display andcolor filter are shown in FIG. 1. The liquid crystal display comprisestwo panels. The upper panel comprises a first polarizer (71), a glass orother rigid substrate (30), an optional adhesion layer, a black matrixformed by either conventional lithographic techniques, via thermalprinting or by other means. The materials comprising the black matrixmay be either inorganic (e.g. chromium, chromium oxide, etc.) or organic(e.g. black pigmented photoresist). The upper plate further comprisesthe color filter layer comprising separate red, green and blue subpixels (12′), a protective organic planarizing layer (40), a transparentelectrical conductor (typically indium tin oxide) (73), and an alignmentlayer (74) which serves to template the liquid crystal orientation. Theupper and lower plates are separated by rigid mechanical spacers (75)that maintain a fixed separation between the two plates and that furtherserve to define the cell wherein the liquid crystal solution iscontained. The lower plate of the LCD display is comprised of a secondalignment layer (76), transparent conductor (77) and glass or otherrigid material as substrate (78) and finally a second polarizer (72).Not shown in the schematic diagram are the drive electronics thatcontrol the orientation of the liquid crystal. Typical modern LCDdisplays employ an array of thin film transistor circuits (not shown)(one circuit for each RGB sub-pixel) which are fabricated on the lowerplate of the LCD display. Finally, a backlight (79) is located below thelower plate to provide illumination of the display. LCD displaysemploying reflected ambient illumination may also be used with the colorfilters of this invention.

EXAMPLES

These non-limiting examples demonstrate the processes and productsclaimed and described herein. All temperatures throughout thespecification are in ° C. (degrees Centigrade) and all percentages areweight percentages unless indicated otherwise. Sìgma-Aldrich, St. Louis,Mo., is a useful source of many of the materials used here. Glossary:NIR-1 2-[2-[2-Chloro-3[2-(1,3-dihydro-1,1 dimethyl-3-(4dimethyl-3(4sulfobutyl)-2H-benz[e]indol-2-yllidene)ethylidene]-1-cyclohexen-1-yl]ethenyl]-1,1-dimethyl-3-(sulfobutyl)-1H-benz[e]indolium, inner salt, (H.W. Sands Corp., Jupiter, FL) FSA Zonyl ®FSA fluoro surfactant; 25% solids in water and isopropanol, [CAS No.57534-45-7] A lithium carboxylate anionic fluorosurfactant having thefollowing structure: RfCH2CH2SCH2CH2CO2Li where Rf = F(CF2CF2)x andwhere x = 1 to 9 (DuPont, Wilmington, DE) PEG 300 Polyethylene glycol300 [CAS No. 25322-68-3], 100%, Scientific Polymer Products, Inc.,Ontario, NY) Melinex ® 573 102 micron clear PET base(DuPontTeijinFilms ™, a joint venture of E.I. du Pont de Nemours &Company) Creo Model 3244 Spectrum Trendsetter Creo Inc., Vancouver,Canada Wyko Model RST Plus Surface Profiler Wyko Corp., Tucson, ArizonaCorning 1737 display grade glass Corning Glass Company, Corning, NYVAZO ® 67 DuPont, Wilmington, DE CRONAR ® 471X DuPont, Wilmington, DEELVAX ® 550 DuPont, Wilmington, DE POLYSTEP B-7 Stepan Co., Northfield,IL Butyl Cellosolve [111-76-2] Aldrich, Milwaukee, WI2-amino-2-methyl-1-propanol [124-68-5] Aldrich, Milwaukee, WIN,N-dimethylethanolamine (DMEA) [108-01-0]] Aldrich, Milwaukee, WI

DEFINITIONS

T_(g) (Glass transition temperature) values reported were mid-pointtemperatures in degrees Centigrade from DSC scans recorded according toASTM D3418-82.

Molecular weights were measured by standard gel permeationchromatography (GPC) by standard techniques vs. poly(methylmethacrylate) standards in THF solution.

Dynamic light scattering was performed using Brookhaven InstrumentBI-9000AT digital correlator (Brookhaven Instruments, Brookhaven, N.Y.).An argon-ion laser with wavelength 488 nm and power 200 mW was used.Measurements were made at room temperature with scattering angle 60°.The samples were diluted 200 μL into 20 mL water then again 100 μL into20 mL water, and then filtered with 0.45 micron filter. The results arereported as diameter (particle size) in nm units. For generaldiscussions of the determination of particle sizes by quasielastic lightscattering, see Paint and Surface Coatings: Theory and Practice, ed. ByR. Lombourne, Ellis Horwood Ltd., West Sussex, England, 1987, pp.296-299, and The Application of Laser Light Scattering to the Study of35 Biological Motion, ed. By J. C. Earnshaw and M. W. Steer, PlenumPress, NY, 1983, pp. 53-76.

Solids content was measured by putting about 5 grams of acrylic latex ina tared, 5-cm aluminum pan, which was placed in a 75° C. vacuum oven atabout 400 mm Hg vacuum for 1 to 2 days. Percent solids was calculated bydividing the final sample weight by the initial sample weight.

Coating weights were measured by cutting out and weighting a 1 dm² pieceof film, removing the coating by rubbing with a paper towel moistened ineither methanol or acetone, drying the film for several minutes, andreweighing. Coating weights are the difference in weights of the beforeand after film in mg, units: mg/dm².

Color Filter Preparation

Receiver Latexes

PR-8

A 3-liter, round bottom flask was equipped with a condenser, additionfunnel, initiating solution inlet port, mechanical stirrer, heater andtemperature controller probe, with the contents maintained under anitrogen atmosphere. The flask was charged with 700 grams of deionizedwater and 6.90 grams of POLYSTEP B-7. A first initiating solution of0.40 grams ammonium persulfate dissolved in 100 mL of deionized waterwas prepared. A first monomer blend of 140.0 grams methyl methacrylate,4.0 grams glycidyl methacrylate, and 50.0 grams n-butyl acrylate wasprepared and placed in the addition funnel. A second monomer blend of140.0 grams methyl methacrylate, 4.0 grams glycidyl methacrylate, 50.0grams n-butyl acrylate, and 12.0 grams of methacrylic acid was prepared.While stirring, the contents of the reaction flask were heated to 85° C.and maintained at that temperature, within a range of 3° C., through thefollowing steps.

The synthesis of the acrylic latex was initiated by the first additionto the flask of 80 mL of the first initiating solution, followed withinone minute by the second addition of 20 mL of the first monomer blendfrom the addition funnel. These two additions were complete in less thanone minute. The remaining portion of first monomer blend in the additionfunnel was added to the flask, beginning within two minutes, at aconstant rate over a period of 60 minutes. At the end of the addition ofthe first monomer blend, the second monomer blend was promptly addedwithin two minutes to the addition funnel and immediately thereafter wasadded to the flask at a constant rate over a period of 60 minutes total.When the addition of the second monomer blend was complete, theremaining initiating solution was promptly added in less than oneminute. Stirring of the contents of the flask at 85° C. plus or minus 3°C. was maintained for 30 minutes after the completion of the addition ofthe initiating solution. Thereafter the contents of the reaction flaskwere cooled to ambient temperature and filtered through a fine paintstrainer, (Paul N. Gardner Company, Inc. Pompano Beach, Fla., Itemnumber ST-F 60×48 mesh) to provide the acrylic latex PR-8.

The acrylic latex had a particle size of 92 nm, 33.5% solids, and aT_(g) of 72° C.

PR-9

A 3-liter, round bottom flask was equipped with a condenser, additionfunnel, initiating solution inlet port, mechanical stirrer, heater andtemperature controller probe, with the contents maintained under anitrogen atmosphere. The flask was charged with 700 grams of deionizedwater and 6.90 grams of POLYSTEP B-7. A first initiating solution of0.40 grams ammonium persulfate dissolved in 100 mL of deionized waterwas prepared. A first monomer blend of 110.0 grams methyl methacrylate,4.0 grams glycidyl methacrylate, and 80.0 grams n-butyl acrylate wasprepared and placed in the addition funnel. A second monomer blend of110.0 grams methyl methacrylate, 4.0 grams glycidyl methacrylate, 80.0grams n-butyl acrylate, and 12.0 grams of methacrylic acid was prepared.While stirring, the contents of the reaction flask were heated to 85° C.and maintained at that temperature, within a range of 3° C., through thefollowing steps.

The synthesis of the acrylic latex was initiated by the first additionto the flask of 80 mL of the first initiating solution, followed withinone minute by the second addition of 20 mL of the first monomer blendfrom the addition funnel. These two additions were complete in less thanone minute. The remaining portion of first monomer blend in the additionfunnel was added to the flask, beginning within two minutes, at aconstant rate over a period of 60 minutes. At the end of the addition ofthe first monomer blend, the second monomer blend was promptly addedwithin two minutes to the addition funnel and immediately thereafter wasadded to the flask at a constant rate over a period of 60 minutes total.When the addition of the second monomer blend was complete, theremaining initiating solution was promptly added in less than oneminute. Stirring of the contents of the flask at 85° C. plus or minus 3°C. was maintained for 30 minutes after the completion of the addition ofthe initiating solution. Thereafter the contents of the reaction flaskwere cooled to ambient temperature, and filtered through a fine paintstrainer, (Paul N. Gardner Company, Inc. Pompano Beach, Fla., Itemnumber ST-F 60×48 mesh) to provide the acrylic latex PR-9.

The acrylic latex had a particle size of 94 nm, 33.4% solids, and aT_(g) of 39° C.

Receiver Film

A receiver film (FR-1) was prepared as follows. A coating compositionwas prepared in a 40-Liter stainless steel vessel with the followingingredients: 3241.69 grams of deionized water, 144.08 grams of Zonyl®FSA, 2161.13 grams of Butyl Cellosolve, 9148.78 grams of PR-8, and21323.13 grams of PR-9, added to the vessel in the stated order. Thecomposition was coated to a dry coating weight of 13.1 mg/dm² on asupporting base. The coating composition was coated on the Elvax® 550surface of a supporting base of 64 micron thick Elvax® 550 (ethylenevinyl acetate copolymer, DuPont) coated onto 102 micron thick Cronar®471X polyester (DuPont, Wilmington, Del.). The coated supporting basewas dried at temperatures which increased from an initial value of about38° C. to a final value of about 65° C. over a period of about 5minutes. After the film was dried, it was interleaved with OSM mattepolyethylene film (Tredegar Co., New Bern, N.C.) and run at ambienttemperature through nip rolls at 650 kPa to emboss the polyethylenepattern onto the receiver surface. The polyethylene film was left on thereceiver surface until just prior to imaging to prevent contamination ofthe coated surface during subsequent handling.

Donor Element

Dispersing Resin DR-3

Pigment dispersant DR-3 was prepared by the cobalt chain transfer graftcopolymer methods as described in U.S. Pat. No. 5,231,131, Chu, et. al.The composition is listed in Table 1. The composition before the -g- waspolymerized by cobalt chain transfer polymerization to an oligomer witha polymerizable group at the end. This oligomer was then copolymerizedwith the remaining monomer mixture to form a graft copolymer. TABLE 1Composition information for DR-3. Dispersing Polymer Monomer ResinComponents Composition Solvent DR-3 (69)nBA/MA/AA- (45.5/45.5/9)-g-Methyl ethyl g-(31)MMA/MAA (28.75/71.25) ketone/isopropanolPigment Dispersions

The PD-K1 pigment dispersion was prepared from Degussa W6620 carbonblack and DR-3. The pigment dispersion was prepared at 15% solids with apigment to dispersant ratio (P/D) of 2.0, according to the proceduresdescribed in U.S. Pat. No. 5,231,131, Chu: A mixture of 323.08 grams ofwater, 33.30 grams of dispersant solution, and 3.62 grams of2-amino-2-methyl-1-propanol was charged, along with 10 40.00 grams ofDegussa W6220 carbon black, to an attritor (Apollo® Trick Titanium,Troy, Mich.). The attritor contained 850 grams of 0.8-1.0 micronzirconia media. The mixture was processed for 22 hours, keeping thetemperature below 38° C. Filtration through a 1 micron filter producedthe pigment dispersion.

Dispersions PD-R5, PD-G4 and PD-B2 were prepared in the same manner asPD-K1 using the materials and conditions shown in Table 2. TABLE 2Compositions of Pigment Dispersions Pigment Pigment Dispersion PigmentDesignation P/D PD-R5 Chromophthal Red 3B Pigment Red 2.0 (Ciba) 177PD-G4 Irgalite Green 6G Pigment 8.0 (Ciba) Green 36 PD-B2 Irgalite BlueGLO Pigment Blue 4.0 (Ciba) 15:3 PD-K1 W6220 (Degussa) Carbon Black 2.0Binder ResinsPR-5

A 3-liter, round bottom flask was equipped with a condenser, additionfunnel, initiating solution inlet port, mechanical stirrer, heater andtemperature controller probe, with the contents maintained under anitrogen atmosphere. The flask was charged with 700 grams of deionizedwater and 6.90 grams of POLYSTEP B-7. A first initiating solution of0.40 grams ammonium persulfate dissolved in 100 mL of deionized waterwas prepared. A first monomer blend of 90.0 grams methyl methacrylate,4.0 grams glycidyl methacrylate, and 100.0 grams n-butyl acrylate wasprepared and placed in the addition funnel. A second monomer blend of90.0 grams methyl methacrylate, 4.0 grams glycidyl methacrylate, 100.0grams n-butyl acrylate, and 12.0 grams of methacrylic acid was prepared.While stirring, the contents of the reaction flask were heated to 85° C.and maintained at that temperature, within a range of 3° C., through thefollowing steps.

The synthesis of the acrylic latex was initiated by the first additionto the flask of 80 mL of the first initiating solution, followed withinone minute by the second addition of 20 mL of the first monomer blendfrom the addition funnel. These two additions were complete in less thanone minute. The remaining portion of first monomer blend in the additionfunnel was added to the flask, beginning within two minutes, at aconstant rate over a period of 60 minutes. At the end of the addition ofthe first monomer blend, the second monomer blend was promptly addedwithin two minutes to the addition funnel and immediately thereafter wasadded to the flask at a constant rate over a period of 60 minutes total.When the addition of the second monomer blend was complete, theremaining initiating solution was promptly added in less than oneminute. Stirring of the contents of the flask at 85°0 C. plus or minus3° C. was maintained for 30 minutes after the completion of the additionof the initiating solution.

Thereafter the contents of the reaction flask were cooled to ambienttemperature and filtered through a fine paint strainer, (Paul N. GardnerCompany, Inc. Pompano Beach, Fla., Item number ST-F 60×48 mesh) toprovide the acrylic latex PR-5.

The acrylic latex had a particle size of 81 nm, 33.3% solids, and aT_(g) of 113° C.

PR-6

A 3-liter, round bottom flask was equipped with a condenser, additionfunnel, initiating solution inlet port, mechanical stirrer, heater and35 temperature controller probe, with the contents maintained under anitrogen atmosphere. The flask was charged with 700 grams of deionizedwater and 6.90 grams of POLYSTEP B-7. A first initiating solution of0.20 grams ammonium persulfate dissolved in 100 mL of deionized waterwas prepared. A first monomer blend of 10.0 grams methyl methacrylate,20.0 grams styrene, 4.0 grams glycidyl methacrylate, and 160.0 gramsn-butyl acrylate was prepared and placed in the addition funnel. Asecond monomer blend of 10.0 grams methyl methacrylate, 20.0 gramsstyrene, 4.0 grams glycidyl methacrylate, 160.0 grams n-butyl acrylate,and 12.0 grams of methacrylic acid was prepared. While stirring, thecontents of the reaction flask were heated to 85° C. and maintained atthat temperature, within a range of 3° C., through the following steps.

The synthesis of the acrylic latex was initiated by the first additionto the flask of 80 mL of the first initiating solution, followed withinone minute by the second addition of 20 mL of the first monomer blendfrom the addition funnel. These two additions were complete in less thanone minute. The remaining portion of first monomer blend in the additionfunnel was added to the flask, beginning within two minutes, at aconstant rate over a period of 60 minutes. At the end of the addition ofthe first monomer blend, the second monomer blend was promptly addedwithin two minutes to the addition funnel and immediately thereafter wasadded to the flask at a constant rate over a period of 60 minutes total.When the addition of the second monomer blend was complete, theremaining initiating solution was promptly added in less than oneminute. Stirring of the contents of the flask at 85° C. plus or minus 3°C. was maintained for 30 minutes after the completion of the addition ofthe initiating solution. Thereafter the contents of the reaction flaskwere cooled to ambient temperature and filtered through a fine paintstrainer, (Paul N. Gardner Company, Inc. Pompano Beach, Fla., Itemnumber ST-F 60×48 mesh) to provide the acrylic latex PR-6.

The acrylic latex had a particle size of 81 nm, 33.7% solids, and aT_(g) of −21° C.

Coating/Drying Conditions

Donor film formulations are summarized in Table 3. The amounts ofmaterials listed Table 3 were added to a stirred 40-L stainless steelvessel under air in the order listed in Table 3. The formulations werethen stirred for 24-48 hours and filtered through a 5μ filter. Theseformulations were coated onto the specified film bases and dried attemperatures that increased from an initial value of about 38° C. to afinal value of about 65° C. over about 5 minutes. TABLE 3 Gram Weightsof Ingredients for Color Filter Donor Coating. Ingredient Red Green BlueBlack Deionized Water 3942.00 4032.00 3960.00 3882.60 Zonyl ® FSA 14.4034.20 14.40 43.20 PR-5 2754.00 2538.00 2448.00 2754.00 PR-6 302.40446.40 613.80 446.40 DMEA, 10% in water 109.80 106.20 109.80 109.80PEG-300 54.00 NIR-1 54.00 39.60 54.00 PD-R5 10818.00 PD-G4 10764.00PD-B2 10800.00 PD-K1 10764.00Imaging

Color donors were imaged on the Trendsetter® in the order R, B, G, Kdirectly onto the receiver sheet. The power settings (Wpower, watts)were: R=6.35, B=7.20, G=5.45, K=5.90. The drum speeds (rpm) were: R=108,B=120, G=110, K=120.

The image used for preparation of the color filter was composed ofalternating R/G/B stripes with widths of 110 microns. The stripes wereseparated by gaps of 10 microns. A black grid was overprinted on thecolor stripes; the width of the black lines was 30 microns and hence a10-micron portion of the black grid overlapped each color stripe oneither side of the gap between stripes. The black grid had a pitch of200 microns in the direction orthogonal to the color stripes. Each colorfilter image was 13 cm square, and there were twelve images per receiversheet.

Lamination of Filter to Glass

Glass Preparation

Pieces of Corning 1737 display grade glass (18 cm square) were 20 rinsedwith deionized water, rinsed and gently scrubbed with soapy water(Micro® brand cleaner), rinsed with deionized water, rinsed withisopropanol, rinsed with deionized water, and then dried vertically in astream of dry nitrogen at room temperature.

Glass Treating Polymer, AP-1

A 3-liter, round bottom flask was equipped with a condenser, additionfunnel, initiating solution inlet port, mechanical stirrer, heater andtemperature controller probe, with the contents maintained under anitrogen atmosphere. The flask was charged with 700 grams of deionizedwater and 6.90 grams of POLYSTEP B-7. A first initiating solution of0.40 grams ammonium persulfate dissolved in 100 mL of deionized waterwas prepared. A first monomer blend of 66.0 grams methyl methacrylate,4.0 grams glycidyl methacrylate, and 110.0 grams n-butyl acrylate wasprepared and placed in the addition funnel. A second monomer blend of66.0 grams methyl methacrylate, 4.0 grams glycidyl methacrylate, 110.0grams n-butyl acrylate, and 40.0 grams of methacrylic acid was prepared.While stirring, the contents of the reaction flask were heated to 85° C.and maintained at that temperature, within a range of 3° C., through thefollowing steps.

The synthesis of the acrylic latex was initiated by the first additionto the flask of 80 mL of the first initiating solution, followed withinone minute by the second addition of 20 mL of the first monomer blendfrom the addition funnel. These two additions were complete in less thanone minute. The remaining portion of first monomer blend in the additionfunnel was added to the flask, beginning within two minutes, at aconstant rate over a period of 60 minutes. At the end of the addition ofthe first monomer blend, the second monomer blend was promptly addedwithin two minutes to the addition funnel and immediately thereafter wasadded to the flask at a constant rate over a period of 60 minutes total.When the addition of the second monomer blend was complete, theremaining initiating solution was promptly added in less than oneminute. Stirring of the contents of the flask at 85° C. plus or minus 3°C. was maintained for 30 minutes after the completion of the addition ofthe initiating solution. Thereafter the contents of the reaction flaskwere cooled to ambient temperature and filtered through a fine paintstrainer, (Paul N. Gardner Company, Inc. Pompano Beach, Fla., Itemnumber ST-F 60×48 mesh) to provide the acrylic latex, AP-1.

The acrylic latex had particle size 88 nm, 33.5% solids, and T_(g) 4° C.

Lamination of Color Filters to Glass

The polymer, AP-1, was diluted to 5% solids with water containing 6%butyl cellosolve. This coating mixture was coated onto the preparedglass samples with a spin coater at 1000 rpm. The coated glass was driedat room temperature for 24 hours. The thickness of the adhesive coatingwas 150 nm. Thickness was measured by scratching a small area to bareglass and measuring thickness with the Wyko. The individual colorfilters were laminated to the adhesive-coated glass samples in aTetrahedron Model MTP13 laminator at 80° C. for three minutes and 7megapascals pressure. The laminated color filters were allowed to coolto room temperature and then the backing film was peeled off.

Planarizer Film Preparation

Chain Transfer Agent Solution CTA-1

A chain transfer agent solution used in the following acrylic latexsynthesis was prepared as described by the methods of U.S. Pat. No.5,362,826, Berge, et. al. and U.S. Pat. No. 5,324,879, Hawthorne.

A 500-liter reactor was equipped with a reflux condenser and nitrogenatmosphere. The reactor was charged with methyl ethyl ketone (42.5 kg)and isopropyl-bis(borondifluorodimethylglyoximato) cobaltate (III) (CoIII DMG) (104 g) and the contents brought to reflux. A first mixture ofCo III DMG (26.0 g), methyl methacrylate (260 kg), and methyl ethylketone (10.6 kg) was added in a first feed to the reactor at a constantrate over a total period of 4 hours. Starting at the same time as thestart of the first feed, a second mixture of VAZO® 67 (5.21 kg) andmethyl ethyl ketone (53.1 kg) was added in a second feed to the reactorat a constant rate over a total period of 5 hours. After the completionof the second feed in 5 hours, the reactor contents were kept at refluxfor a further 30 minutes. After cooling to ambient temperature, a 70 wt% solids solution of the chain transfer agent, CTA-1, was obtained.

PR-1

An acrylic latex of controlled molecular weight polymer resin wasprepared as detailed below using the chain transfer agent solutionaccording to the method in U.S. Pat. No. 5,773,534, Antonelli, et. al.

A 3-liter, round bottom flask was equipped with a condenser, additionfunnel, initiating solution inlet port, mechanical stirrer, heater andtemperature controller probe, with the contents maintained under anitrogen atmosphere. The flask was charged with 700 grams of deionizedwater and 6.90 grams of POLYSTEP B-7. A first initiating solution of0.40 grams ammonium persulfate dissolved in 100 mL of deionized waterwas prepared. A first monomer blend of 122 grams methyl methacrylate,4.0 grams glycidyl methacrylate, 60.0 grams n-butyl acrylate and 8.0grams chain transfer agent solution was prepared and placed in theaddition funnel. A second monomer blend of 122.0 grams methylmethacrylate, 4.0 grams glycidyl methacrylate, 60 grams n-butylacrylate, 12.0 grams of methacrylic acid and 8.0 grams chain transferagent solution was prepared. While stirring, the contents of thereaction flask were heated to 85° C. and maintained at that temperature,within a range of 3° C., through the following steps.

The synthesis of the acrylic latex was initiated by the first additionto the flask of 80 mL of the first initiating solution, followed withinone minute by the second addition of 20 mL of the first monomer blendfrom the addition funnel. These two additions were complete in less thanone minute. The remaining portion of first monomer blend in the additionfunnel was added to the flask, beginning within two minutes, at aconstant rate over a period of 60 minutes. At the end of the addition ofthe first monomer blend, the second monomer blend was promptly addedwithin two minutes to the addition funnel and immediately thereafter wasadded to the flask at a constant rate over a period of 60 minutes total.When the addition of the second monomer blend was complete, theremaining initiating solution was promptly added in less than oneminute. Stirring of the contents of the flask at 85° C. plus or minus 3°C. was maintained for 30 minutes after the completion of the addition ofthe initiating solution. Thereafter the contents of the reaction flaskwere cooled to ambient temperature and filtered through a fine paintstrainer, (Paul N. Gardner Company, Inc. Pompano Beach, Fla., Itemnumber ST-F 60×48 mesh) to provide the acrylic latex PR-1.

Properties of this latex are summarized in Table 3.

PR-10

An acrylic latex, PR-10 of controlled molecular weight polymer resin wasprepared as detailed below using the chain transfer agent solutionaccording to the method in U.S. Pat. No. 5,773,534, Antonelli, et. al.

A 3-liter, round bottom flask was equipped with a condenser, additionfunnel, initiating solution inlet port, mechanical stirrer, heater andtemperature controller probe, with the contents maintained under anitrogen atmosphere. The flask was charged with 700 grams of deionizedwater and 6.90 grams of POLYSTEP B-7. A first initiating solution of0.40 grams ammonium persulfate dissolved in 100 mL of deionized waterwas prepared. A first monomer blend of 126.0 grams methyl methacrylate,4.0 grams glycidyl methacrylate, 60.0 grams n-butyl acrylate and 4.0grams chain transfer agent solution was prepared and placed in theaddition funnel. A second monomer blend of 126.0 grams methylmethacrylate, 4.0 grams glycidyl methacrylate, 60 grams n-butylacrylate, 12.0 grams of methacrylic acid and 4.0 grams chain transferagent solution was prepared. While stirring, the contents of thereaction flask were heated to 85° C. and maintained at that temperature,within a range of 3° C., through the following steps.

The synthesis of the acrylic latex was initiated by the first additionto the flask of 80 mL of the first initiating solution, followed withinone minute by the second addition of 20 mL of the first monomer blendfrom the addition funnel. These two additions were complete in less thanone minute. The remaining portion of first monomer blend in the additionfunnel was added to the flask, beginning within two minutes, at aconstant rate over a period of 60 minutes. At the end of the addition ofthe first monomer blend, the second monomer blend was promptly addedwithin two minutes to the addition funnel and immediately thereafter wasadded to the flask at a constant rate over a period of 60 minutes total.When the addition of the second monomer blend was complete, theremaining initiating solution was promptly added in less than oneminute. Stirring of the contents of the flask at 85° C. plus or minus 3°C. was maintained for 30 minutes after the completion of the addition ofthe initiating solution. Thereafter the contents of the reaction flaskwere cooled to ambient temperature and filtered through a fine paintstrainer, (Paul N. Gardner Company, Inc. Pompano Beach, Fla., Itemnumber ST-F 60×48 mesh) to provide the acrylic latex, PR-10.

Properties of this latex are summarized in Table 3.

PR-11

An acrylic latex E99339-71 of controlled molecular weight polymer resinwas prepared as detailed below using the chain transfer agent solutionaccording to the method in U.S. Pat. No. 5,773,534, Antonelli, et. al.

A 3-liter, round bottom flask was equipped with a condenser, additionfunnel, initiating solution inlet port, mechanical stirrer, heater andtemperature controller probe, with the contents maintained under anitrogen atmosphere. The flask was charged with 700 grams of deionizedwater and 6.90 grams of POLYSTEP B-7. A first initiating solution of0.40 grams ammonium persulfate dissolved in 100 mL of deionized waterwas prepared. A first monomer blend of 128.0 grams methyl methacrylate,4.0 grams glycidyl methacrylate, 60.0 grams n-butyl acrylate and 2.0grams chain transfer agent solution was prepared and placed in theaddition funnel. A second monomer blend of 128.0 grams methylmethacrylate, 4.0 grams glycidyl methacrylate, 60 grams n-butylacrylate, 12.0 grams of methacrylic acid and 2.0 grams chain transferagent solution was prepared. While stirring, the contents of thereaction flask were heated to 85° C. and maintained at that temperature,within a range of 3° C., through the following steps.

The synthesis of the acrylic latex was initiated by the first additionto the flask of 80 mL of the first initiating solution, followed withinone minute by the second addition of 20 mL of the first monomer blendfrom the addition funnel. These two additions were complete in less thanone minute. The remaining portion of first monomer blend in the additionfunnel was added to the flask, beginning within two minutes, at aconstant rate over a period of 60 minutes. At the end of the addition ofthe first monomer blend, the second monomer blend was promptly addedwithin two minutes to the addition funnel and immediately thereafter wasadded to the flask at a constant rate over a period of 60 minutes total.When the addition of the second monomer blend was complete, theremaining initiating solution was promptly added in less than oneminute. Stirring of the contents of the flask at 85° C. plus or minus 3°C. was maintained for 30 minutes after the completion of the addition ofthe initiating solution. Thereafter the contents of the reaction flaskwere cooled to ambient temperature and filtered through a fine paintstrainer, (Paul N. Gardner Company, Inc. Pompano Beach, Fla., Itemnumber ST-F 60×48 mesh) to provide the acrylic latex E99339-71.

Properties of this latex are summarized in Table 4. TABLE 4 PROPERTIESOF PLANARIZING LATEXES Summary of Planarizing Latex Properties ParticleLatex % CTA-1 Tg (° C.) Diameter (nm) Mn, Mw PR-1 4 55 86 20,000, 85,000PR-10 2 60 91 26,000, 118,000 PR-11 1 60 91 22,000, 149,000Lamination of Planarizer

Each of the three planarizing latexes was coated onto Melinex® 574(DuPont) at four thicknesses as follows: A coating composition wasprepared from each planarizing latex by mixing, in order, 4.50 grams oflatex, 4.76 grams of water, 0.70 grams of butyl cellosolve, and 0.040grams of Zonyl® FSA. Each coating composition was then coated onto fourpieces of Melinex® 574 with #6, #8, #10, and #13 Meyer rods. The coatedfilms were then air dried at ambient temperature for at least 24 hoursbefore use. Thicknesses of the #6, #8, #10, and #13 rod coatings weredetermined to be 1.46, 2.07, 2.41, and 3.36 microns, respectively.Thicknesses of the planarizer layers were measured by laminating some ofthe film to a microscope slide, pretreated with an adhesive layer,scratching the resulting film to bare glass, and measuring thickness onWyko Model RST Plus Surface Profiler (Wyko Corp., Tucson, Ariz.).

The planarizing films were then each placed coated side down on a colorfilter on glass and then laminated in the Tetrahedron press laminator at130° C. for three minutes at 14 megapascals pressure. The planarizedcolor filters were then cooled to room temperature before the Melinex®was peeled off. The planarized color filters were then annealed in avacuum oven at 150° C. for 90 minutes.

Surface Roughness Measurements

Wyko Measurements

The roughness of the samples was measured with the Wyko opticalprofilometer. The root-mean-square (RMS) roughness, Rq (nm), wasmeasured at five locations on each sample: center, left and right edges,and left and right bottom corners. The results were then averaged, andare summarized in Table 5. TABLE 5 RMS surface roughness (Rq, nm) forplanarized samples Coating Rod Thickness PR-1 PR-10 PR-11 #6 1.46 134151 165 #8 2.07 122 153 189 #10 2.41 65 145 171 #13 3.36 53 114 —

1. A planarizing element comprising planarizing layer, wherein theplanarizing layer comprises a crosslinkable binder, and wherein thecrosslinkable binder has a weight average molecular weight of about20,000 to about 110,000.
 2. The planarizing element of claim 1 whereinthe crosslinkable binder has a weight average molecular weight of about30,000 to about 100,000.
 3. The planarizing element of claim 1 whereinthe crosslinkable binder has a weight average molecular weight of 50,000to about 85,000.
 4. The planarizing element of claim 1 wherein thecrosslinkable binder is a polymer prepared by emulsion polymerization orsolution polymerization.
 5. The planarizing element of claim 4 whereinthe crosslinkable binder is prepared from monomers selected from thegroup consisting of acrylic acid and esters, methacrylic acid andesters, and styrene.
 6. The planarizing element of claim 1 furthercomprising coating aids, UV stabilizers, UV-filters, UV absorbers, smallmolecule crosslinking aids, plasticizers, flow additives, adhesionpromoters, antistatic agents, and surfactants.
 7. A method for making acolor image comprising: (1) imagewise exposing to laser radiation alaserable assemblage comprising: (A) a donor element comprising athermally imageable layer, and (B) a receiver element comprising: (a) areceiver support; and (b) an image receiving layer provided on thesurface of the receiver support; whereby the exposed areas of thethermally imageable layer are transferred to the receiver element toform a colorant-containing image on the image receiving layer; and (2)separating the donor element (A) from the receiver element (B), therebyrevealing the colorant-containing image on the image receiving layer ofthe receiver element; (3) optionally applying the colorant-containingimage on the image receiving layer of the receiver element to apermanent substrate, and removing the receiver support to transfer thecolorant-containing image on the image receiving layer to the permanentsubstrate, and (4) applying a planarizing element comprising a supportand a planarizing layer to the image receiving layer, and removing thesupport, wherein the planarizing layer is adjacent thecolorant-containing image, and wherein the planarizing layer comprises acrosslinkable binder having a weight average molecular weight of about20,000 to about 110,000.
 8. The method of claim 7 wherein thecrosslinkable binder has a weight average molecular weight of about30,000 to about 100,000.
 9. The method of claim 8 wherein thecrosslinkable binder has a weight average molecular weight of 50,000 toabout 85,000.
 10. The method of claim 7 wherein thermally imageablelayer, image receiving layer or both comprise a crosslinkable binderhaving a number average molecular weight of about 1,500 to about 70,000.11. The method for making a color image of claim 7 wherein step (3) isoptional, and the receiver support is a transparent material.
 12. Themethod for making a color image of claim 7 wherein permanent substrateis a transparent material.
 13. The method for making a color image ofclaim 11 or 12 wherein transparent material is glass.
 14. The method formaking a color image of claim 11 or 12 wherein transparent material istreated glass.
 15. The method for making a color image of claim 11 or 12wherein the transparent material is a rigid plastic,
 16. The method formaking a color image of claim 15 wherein the rigid plastic ispolycarbonate.
 17. The method for making a color image of claim 7wherein the crosslinkable binder is a polymer prepared by emulsionpolymerization or solution polymerization.
 18. The method for making acolor image of claim 17 wherein the crosslinkable binder is preparedfrom monomers selected from the group consisting of acrylic acid andesters, methacrylic acid and esters, and styrene.
 19. The method formaking a color image of claim 7 wherein the applying is by laminating.20. A method for making a color image comprising: (1) imagewise exposingto laser radiation a laserable assemblage comprising: (A) a donorelement having a thermally imageable layer, and (B) a permanentsubstrate; whereby the exposed areas of the thermally imageable layerare transferred to the permanent substrate to form a colorant-containingimage on the permanent substrate; (2) separating the donor element (A)from the permanent substrate (B), thereby revealing thecolorant-containing image on the permanent substrate, and (3) applying aplanarizing element comprising a support and a planarizing layer to thecolorant-containing image, and removing the support, wherein theplanarizing layer is adjacent the colorant-containing image, and whereinthe planarizing layer comprises a crosslinkable binder having a weightaverage molecular weight of about 20,000 to about 110,000.
 21. Themethod of claim 20 wherein the crosslinkable binder has a weight averagemolecular weight of about 30,000 to about 100,000.
 22. The planarizingelement of claim 21 wherein the crosslinkable binder has a weightaverage molecular weight of 50,000 to about 85,000.
 23. The method formaking a color image of claim 20 wherein permanent substrate is atransparent material.
 24. The method for making a color image of claim23 wherein transparent material is glass.
 25. The method for making acolor image of claim 23 wherein transparent material is treated glass.26. The method for making a color image of claim 23 wherein thetransparent material is a rigid plastic,
 27. The method for making acolor image of claim 26 wherein the rigid plastic is polycarbonate. 28.A liquid crystal display comprising a color filter, wherein the colorfilter is prepared using a thermal imaging process, and a planarizingelement comprising a planarizing layer having a crosslinkable binder,having a weight average molecular weight of about 20,000 to about110,000.
 29. The liquid crystal display of claim 28 wherein thecrosslinkable binder has a weight average molecular weight of about30,000 to about 100,000.
 30. The liquid crystal display of claim 29wherein the crosslinkable binder has a weight average molecular weightof 50,000 to about 85,000.
 31. The liquid crystal display of claim 28comprising a color filter having a glass substrate.
 32. The liquidcrystal display of claim 31 wherein the glass substrate has a blackmatrix thereon.
 33. The liquid crystal display of claim 32 comprising acolor filter having at least three color images thereon.
 34. The liquidcrystal display of claim 33 wherein the color images are red, blue andgreen.